Such known armchairs comprise so-called vertical "faces" which correspond to the legs, backrest, armrests, edges and ribs of the seat element, etc. . . . and so-called horizontal "faces" which correspond to the seat element and other elements which are substantially parallel thereto. For such armchairs to be stackable, it is necessary in particular that the lines of greatest slope of the so-called vertical faces form a particular angle of fit with respect to the vertical; this angle determines the pitch of stacking as a function of the thickness of these so-called vertical faces and when the so-called vertical faces of the stacked armchairs are in contact with one another; of course, the height of the seat element with its subjacent projections must be less than said pitch, otherwise it determines the latter by abutment.
Numerous models of such a known armchair exist, probably around two hundred, and they may be classified in several types depending on the orientation of the legs.
A first type comprises legs with a section in the form of a rearwardly open V for the rear legs and forwardly open V for the front legs.
A second type comprises rearwardly open V-sectioned front legs, whilst the V-sectioned rear legs are open on the sides.
According to a variant, the rear legs are sectioned in the form of angles open on the sides as well as rearwardly.
A third type comprises legs sectioned as angles open on the sides and forwardly for the front legs and rearwardly for the rear legs.
These armchairs made of moulded plastics material must satisfy numerous imperatives: aesthetics, stability and strength, comfort, aptitude to support, in complete safety, heavy persons or to withstand ill-advised stresses such as tipping on one or two legs, possibility of stacking them for transport and storage, facility of unstacking them, avoiding jamming, minimum storage and transport costs, competitive cost price, . . . . .
In order to conciliate all these imperatives, rules of practice are observed by all manufacturers. For example, the minimum thickness of the legs is of the order of 6 mm and the angle of said legs with respect to the vertical is included between 5 and 8 degrees without ever exceeding this maximum value.
With such rules, it is possible to make a pile of 30 armchairs at a pitch of about 60 mm; this pile, enclosed in a cover, is 2.30 m high, compatible with the free height of the means of transport used.
It is an object of the present invention to increase the storage and transport capacity in order to reduce the cost of these services. The problem to be solved in order to attain this purpose is that of reducing the pitch of stacking.
Once the problem has been set forth, the invention appears obvious. In fact, it suffices to reduce the thickness slightly and to increase the angle of stacking that the line of greatest slope of the so-called vertical faces makes with the vertical, which angle is limited by practice to 8 degrees.
In that case, Directive C-IV 94-i concerning the examination carried out at the European Patent Office indicates that the inventive activity must be assessed at the level of the formulation of the idea or of a problem to be solved.